Applicant's disclosure is directed to a wireless communications network overlay for determining the location of mobile appliances.
The use of wireless communication devices such as telephones, pagers, personal digital assistants, laptop computers, etc., hereinafter referred to collectively as “mobile appliances”, has become prevalent in today's society. Recently, at the urging of public safety groups, there has been increased interest in technology which can determine the geographic position, or “geolocate” a mobile appliance in certain circumstances. For example, the Federal Communication Commission (FCC) has issued a geolocation mandate for providers of wireless telephone communication services that puts in place a schedule and an accuracy standard under which the providers of wireless communications must implement geolocation technology for wireless telephones when used to make a 911 emergency telephone call (FCC 94-102 E911).
In addition to E911 emergency related issues, wireless telecommunications providers are developing location-enabled services for their subscribers including roadside assistance, turn-by-turn driving directions, concierge services, location-specific billing rates and location-specific advertising.
To support FCC E911 rules to locate wireless 911 callers, as well as the location enabled services, the providers of wireless communication services are installing mobile appliance location capabilities into their networks. In operation, these network overlay location systems take measurements on RF transmissions from mobile appliances at base station locations surrounding the mobile appliance, and estimate the location of the mobile appliance with respect to the base stations. Because the geographic location of the base stations is known, the determination of the location of the mobile appliance with respect to the base station permits the geographic location of the mobile appliance to be determined. The RF measurements of the transmitted signal at the base stations can include the time of arrival, the angle of arrival, the signal power, or the unique/repeatable radio propagation path (radio fingerprinting) derivable features. In addition, the geolocation systems can also use collateral information, e.g., information other than that derived for the RF measurement to assist in the geolocation of the mobile appliance, i.e., location of roads, dead-reckoning, topography, map matching etc.
In a network-based geolocation system, the mobile appliance to be located is typically identified and radio channel assignments determined by (a) monitoring the control information transmitted on radio channel for telephone calls being placed by the mobile appliance to detect calls of interest, i.e., 911, (b) a location request provided by a non-mobile appliance source, i.e., an enhanced services provider. Once a mobile appliance to be located has been identified and radio channel assignments determined, the location determining system is first tasked to determine the geolocation of the mobile appliance, and then directed to report the determined position to an appropriate mobile call center or enhanced services provider.
Mobile appliances do not all operate using a common wireless air interface protocol standard. The Telecommunications Industry of America (TIA) and the European Telecommunications Standard Institute (ETSI) are well known standards organizations, each publishing recognized wireless air interface protocol standards. In the past, mobile appliance geolocation systems have been specific to the underlying wireless air interface protocol standard utilized by the mobile appliance being located. Thus, both TIA and ETSI have published geolocation protocol standards for use with their respective wireless air interface communication protocol standards.
The monitoring of the RF transmissions from the mobile appliance to identify calls of interest is known as “tipping”, and generally involves recognizing a call of interest being made from a mobile appliance and collecting the call setup information. Once the mobile appliance is identified and the call setup information is collected, the location determining system can be tasked to geolocate the mobile appliance.
Various methods have been developed to define and coordinate the tasking and reporting functions. One such method involves tasking only and is described in U.S. Pat. No. 5,327,144 to Stilp. This method detects telephone calls of interest by monitoring the control channels of a wireless communication system off-the-air, i.e., receiving RF signals transmitted by the telephones, and detecting call initiations and associated call set-up information directly from the RF signals.
As discussed above, other methods of tasking and/or reporting the location of a mobile appliance can be found in well known geolocation protocol standards published by two recognized standards bodies. The TIA and ETSI each publishes its own standard for tasking and reporting the geolocation of a mobile appliance and define network entities, reference models, and interfaces required to support the geolocation of the mobile appliance.
In the case of a mobile appliance location determining system for use with TIA defined air interfaces, the call setup information includes assigned frequency, time slot or code set is transmitted on a dedicated control channels. For TIA wireless air interface protocol standards, tipping can be accomplished off-the-air by monitoring the dedicated control channel to capture the call setup information, or via wireline interfaces defined in TIA geolocation standards containing tasking messages and data.
In the case of a location determining system for mobile appliances using ETSI defined air interfaces, such as GSM, the call set-up information is transmitted on dynamically allocated control channels on a per-call basis. The call set-up information may also be encrypted. Thus, the ability to identify calls of interest and collect call-set up information off-the-air would require expensive radio processing and decryption resources. As a result, off-the-air tipping is not practical with ETSI defined air interfaces. Instead, the ETSI geolocation standard requires that tipping be accomplished only through messaging on wireline transmissions between network entities, and in some instances requires the mobile appliance to transmit a dedicated location signal to facilitate the geolocation of the mobile appliance.
Presently, wireless communication systems are being deployed in the United States, which operate in accordance with the TIA air interface protocol standard, the ETSI air interface protocol standard, or several other recognized standards, including some proprietary systems such as those used for specialized mobile radio (SMR) and enhanced special mobile radio (ESMR). However, until now, there has not been developed an independent network overlay for determining the location of a mobile appliance for use with the multiple dissimilar wireless air interface protocol standards due, in part, to the nature of the underlying air interfaces. Specifically, the ETSI wireless air interface standard has characteristics, such as control channel allocation and encryption, that make it more difficult for independent network overlay equipment to successfully operate. As a result, the typical geolocation system is oriented to a specific wireless air interface protocol standard, and thus the same geolocation system can not be used to locate two different mobile appliances if the mobile appliances do not operate in networks using a common wireless air interface protocol standard.
The present disclosure is directed to a geolocation and method for locating a mobile appliance without regard to the wireless air interface protocol standard utilized by the mobile appliance. For example, in one embodiment of applicant's disclosure, the tasking is accomplished by monitoring interface points within the existing wireless network (physically wired connections) in a GSM wireless air interface system to determine that a call of interest has been placed and gather associated call set up information to allow a location estimate for the mobile appliance to be determined, and the reporting of the location determination is accomplished using the TIA defined interfaces. The interface point from where tasking is derived is a wireless air interface protocol standard “open interface”, and not specific to one of the geolocation protocol standards.
Accordingly, it is an object of the present disclosure to provide a novel system and method for tasking and reporting the geolocation of a mobile appliance.
It is another object of the present disclosure to provide a novel system and method for geolocating a mobile appliance that is compatible with dissimilar wireless air interface protocol standards.
It is yet another object of the present disclosure to provide a novel system and method for tasking and reporting the geolocation of a mobile appliance using entities operating under different wireless air interface protocol standards.
It is still another the object of the present disclosure to provide a novel system and method for determining the location of a mobile appliance in a GSM wireless air interface system without using the GSM location determining protocol standard.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the disclosure pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.